by Pete Schoeninger
Published in Midwest Flyer – April/May 2019 issue
Q: Last week after the first cold snap of the season, I flew my new (to me) 2007 Cessna 172R. With an outside air temperature of 10 degrees Fahrenheit at altitude in cruise, my oil temp only went up to 140 degrees versus the 180 – 200 degrees I saw most of the summer. Is that normal?
A: Yes, a rule of thumb is that your oil sump temperature should be very roughly 120 degrees warmer than the outside air temperature (OAT). Lycoming (and Continental) recommend a maximum oil temperature in the oil sump of 245 degrees Fahrenheit. To help your engine run a little warmer, you should consider installing cooling baffles. They are recommended for installation when the OAT is below a certain degree. For many C-172s, that temperature is 20 degrees Fahrenheit. Also, some engines can have a partial cover over the oil cooler if the engine has an oil cooler. You may see duct tape used for cooling restrictions, but my recommendation is not to use it. Cooling restrictors (often called baffles) are carefully engineered for your specific engine and installation. Some engines (not yours) may have cowl flaps that can help a little with temperature control.
Q: At the end of January this year, our temperature dropped to 10 degrees Fahrenheit below zero. Both my car and my wife’s car started easily. My mechanic says airplane engines should be preheated when temps are below about 25 degrees Fahrenheit. Why shouldn’t I try and start my airplane engine cold?
A: One reason is modern cars can use much thinner oil than airplane engines, allowing the car engine to turn over relatively easy in cold temps. Your airplane engine design is probably 50-70 years old, so tolerances, timing, priming, etc., are primitive, compared to your car. I’m sure your parents can tell you that 50 years ago, cars were pretty difficult to start with below zero temps, as well.
Q: Pete, exactly what maintenance and equipment records am I required to carry onboard my aircraft at all times? For instance, I just had a new engine monitor and some new avionics installed. Am I required to carry the installation records and operating manual onboard at all times? It’s enough just to haul around the basic aircraft operating manual, let alone every manual for every gizmo I have had installed since the aircraft was manufactured in the 1970s.
A: You don’t need to have information on items previously installed if they were completely removed. You DO, however, need to have a current equipment list showing all CURRENTLY installed equipment, with limitations and Flight Manual Supplements, if required. Maintenance records are not required to be onboard (engine logbooks, for instance), but you need to be able to provide them within a reasonable amount of time if asked to do so by the Federal Aviation Administration.
Q: When you do an appraisal, are you told what the appraised value has to be in order for the aircraft owner to refinance, or to get a loan to buy the aircraft?
A: I turn those requests down, period.
Q: Recently, I saw a news item that a twin-engine airliner returned to the West Coast three times when attempting to fly from the West Coast to Hawaii. What do you know about that?
A: Twin-engine airliners flying long distances over water have to comply with ETOPS, or extended range twin-engine operational performance specifications. These are tighter requirements than over land. In some overland trips, airliners may dispatch with a known discrepancy to another airport if the trip is relatively short. For ETOPS, for instance, you need three generators, more medical oxygen, a higher fuel reserve, etc. If after departure you lose something required, you have to return to the nearest suitable airport. Apparently, the airliner you are referring to may have forgotten a number of things.
Q: My 2007 Cessna 172S has 2450 hours on the engine, and I fly it almost daily. I know flight schools with similar airplanes report getting up to 3,000 hours on their engines. I talked to an airplane salesman who said for valuation purposes, my airplane has a runout engine because engine time exceeds the manufacturer’s recommendation. How could the engine on my aircraft be considered a runout if it is still running okay?
A: Any time you exceed the manufacturer’s recommended overhaul times, you are running a “runout” engine as far as the market goes. I am aware that in a flight school situation where the airplane is flown almost daily, engines like yours occasionally make 3,000 hours. For your airplane, the difference in value between a 2450-hour engine and a 3000-hour engine is negligible.
Q: I have a small FBO with a maintenance shop. A guy recently moved his Baron to our airport. After every maintenance work order, he comes into my office and tries to beat me up on the price of the work completed. I know he just sold his business for $10 million. He doesn’t need a break on the price of anything! I am tempted to tell him to go somewhere else. How would you handle this guy if you were me?
A: If he sold a business for $10 million, he is probably a shrewd businessman. Within reason, I think you should try and get on his good side. If you show him how much your overhead is given employee salaries, workman’s compensation insurance, health insurance for your employees, utility costs, etc., he might realize your charges are reasonable, pay your bill, and think twice before complaining in the future.
Q: One winter day years ago, I had a customer jump up and down in my office after my guys charged him 2.5 hours of labor to change oil in his Baron. He said he used to do it himself in about an hour during the summer. I explained to him that we had to drive to his hangar, pull his airplane outside, start the engine and run it up for a while, open the huge door to our heated shop and let out a lot of hot air to pull the aircraft inside, then drop the oil, remove the oil filters, cut the filters open and inspect them for problems, install a new oil filter and oil, open the huge door to our shop for a second time and let out hot air again, push the airplane outside, run the engine up a second time to make sure there were no oil leaks, then return the airplane to his hangar, and complete paperwork in our shop. I also told him it cost us about $40 worth of heat every time we opened the big hangar doors in winter. We then told him if he could coordinate with us to change his oil when he returned from a flight by leaving the warm airplane in front of our shop, that would save some time/money. He said that he had no idea that we did all those things, and concluded that 2.5 hours for all of that work and expense seemed reasonable. He eventually gave me one of his airplanes to sell on consignment, which I did and made a few bucks, and we continued to maintain his Baron for years afterwards. So, the next time you get what appears to be an outrageous bill for aircraft maintenance, think about what the shop did for the service you received.
Q: What have you seen with values of Cessna 152s? It seems like there are less available and asking prices seem to be rising?
A: You are correct on both counts. Airplanes in general that are commonly used for trainers are gaining in value, with the Cessna 172 probably leading the pack in value increases.
Q: Are there any Murphy’s Laws of FBO or airport management?
A: Sure, here are a few of many I have experienced: 1) We finally persuaded a very nervous prospective student pilot that “little” airplanes were safe and well maintained. We got him into a trainer with one of our flight instructors and the battery was dead…the engine would not turn over. I hand-cranked the engine to start it. While I was doing that, the prospect said, “I want out” and left! 2) If you have two paved runways that cross each other, whenever you have a gear up landing, the airplane will usually end up right at the intersection of your two runways, in effect closing your airport. 3) I had been after local elected officials to visit their airport to see how busy and safe it was. At the agreed time, they arrived. All of my rental airplanes were out doing air work with students, but were due to return within 10-15 minutes. But before my airplanes returned to the traffic pattern, a transient airplane approached to land, dropped in from about 15 feet, took off its gear, and slid to a stop on its belly. That was the first accident on our field in more than a year. Murphy’s Law, indeed. Most FBOs have many more stories to share.
Q: I saw a recent video of a Piper Arrow landing and then smacking into a snowbank trying to stop on the famous ice runway in New Hampshire. Some alleged the landing attempt was with about a 15-mph tailwind. Any thoughts on this one?
A: I am not familiar with that specific incident. That runway is about 2700 feet. But the braking coefficient on glare ice may be as low as 10% of braking efficiency on pavement. If an Arrow normally lands at say 65 mph, with a 15-mph headwind, your groundspeed at touchdown is 50 mph. But if you have a 15-mph tailwind, your touchdown speed is 80 mph. I doubt very much if an airplane would stop in 2700 feet on glare ice if it landed at 80 mph.
Q: As I began my flare to land at night at a strange rural airport a couple of weeks ago, suddenly the runway lights turned off. Fortunately, I had my landing light on and did okay, but what caused that to happen?
A: Probably snowbanks were higher than they should have been between the runway lights and the edge of the runway. Ideally, there should almost be no snow between the runway lights and the edge of the runway, but sometimes in the real world, this is difficult to accomplish, especially with the limited equipment available at some rural airports. FAA officials have suggested dimensions for snow piles, runway lights, etc. You can find them online by searching for FAA Advisory Circular AC 150/5200-30D and look at figure 4.1. Perhaps there should have been a NOTAM alerting you to this dangerous condition.
EDITOR’S NOTE: Pete Schoeninger appraises airplanes for estates, divorces, and partnership buyouts. He is a 40-year general aviation veteran, starting out as a line technician as a teenager, advancing through the ranks to become the co-owner and manager of a fixed base operation, and manager of an airport in a major metropolitan community. For aircraft appraisals, contact Pete at PeterSchoeningerLLC@gmail.com or call 262-533-3056 (peterschoeningerllc.wordpress.com).
DISCLAIMER: The information contained in this column is the expressed opinion of the author only, and readers are advised to seek the advice of others, and refer to aircraft owner manuals, manufacturer recommendations, the Federal Aviation Regulations, FAA Aeronautical Information Manual and instructional materials for guidance on aeronautical matters.